Ultra-sensitive CuAl₂O₄ Nanoflakes for ppb level detection of Isopropanol

Trace-level detection of isopropanol is important for human health monitoring and air quality surveillance. In this work, we report synthesis of high surface area two-dimensional (2D) nanoflakes of CuAl₂O₄ using surfactant-assisted hydrothermal process and its application in ppb level detection of isopropanol. X-ray diffraction revealed the polycrystalline nature of the spinel and a nano crystallite size of 42 nm. The 2D morphology of CuAl₂O₄ was confirmed using field emission scanning electron microscope whereas BET revealed the mesoporous nature and a high surface area of 41.8 m²g^-1. The surface oxidation states of the material were found through X-ray photoelectron spectroscopy. The 2D CuAl₂O₄ demonstrated excellent sensing towards isopropanol with its response varying from 11.8 to 84.5 % (500 ppb–10 ppm) at 300 °C. The limit of detection of the spinel was found to be 56 ppb at its optimum operating temperature of 300 °C. In addition, the sensing layer was found to have response times in range 1101 s for 500 ppb to 168 s for 10 ppm and recovery times in the range 300 s for 500 ppb to 570 s for 10 ppm.